US 20050268570 A2
Abstract of the Disclosure
Floorboards with a mechanical locking system that allows movement between the floorboards when they are joined to form a floating floor.
1. Equipment for production of building panels, having a horizontal plane which is parallel with a panel surface, the equipment comprising a chain, a belt, a pressure shoe and a tool set, the chain and the belt are arranged to displace the building panels relative to the tool set and the pressure shoe, in a feeding direction, the pressure shoe is arranged to press towards a rear side of the building panels, the tool set is arranged to form an edge portion of the building panels when the building panels are displaced relative to the tool set, wherein one of the tools of the tool set forms a guiding surface in the building panels, the pressure shoe has a guiding device which cooperates with the guiding surface and prevents deviations in a direction perpendicular to the feeding direction and parallel to the horizontal plane.
2. The equipment as claimed in
the guiding surface comprises a groove open towards a rear side and that the groove is in an edge portion of the floor board where some parts of the locking system are formed.
3. A semi-floating floor comprises rectangular floorboards joined by a mechanical locking system and in which the joined floorboards have a horizontal plane which is parallel to a floor surface and a vertical plane which is perpendicular to the horizontal plane, said locking system having mechanically cooperating locks for vertical joining parallel to the vertical plane and for horizontal joining parallel to the horizontal plane of a first and a second joint edge and in which locking system the vertical lock comprises a tongue which cooperates with a tongue groove and the horizontal lock comprises a locking element with a locking surface which cooperates with a locking groove, wherein the format, installation pattern and locking system of the floorboards are designed and combined in such a manner that a semi-floating continuous surface, with length or width exceeding 12 m, is adapted to be installed without expansion joints.
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7. A locking system for mechanical joining of floorboards, in which locking system the joined floorboards have a horizontal plane which is parallel to a floor surface and a vertical plane which is perpendicular to the horizontal plane, which locking system has mechanically cooperating locks for vertical joining parallel to the vertical plane and for horizontal joining parallel to the horizontal plane of a first and a second joint edge, and in which locking system the vertical lock comprises a tongue which cooperates with a tongue groove and the horizontal lock comprises a locking element with a locking surface which cooperates with a locking groove, the first and the second joint edge have upper and lower joint edge portions positioned between the tongue and the floor surface, the upper joint edge portions being closer to the floor surface than the lower joint edge portions, and in which locking system, when the floorboards are joined and pressed towards each other the upper joint edge portion in the first joint edge overlaps a lower joint edge portion in the second joint edge.
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The present application claims priority of Swedish Patent Application No. 0400068-3, filed in Sweden on January 13, 2004 and U.S. Provisional Application No. 60/537,891, filed in the United States on January 22, 2004, the entire contents of which are hereby incorporated herein by reference.
The invention relates generally to the technical field of locking systems for floorboards. The invention concerns on the one hand a locking system for floorboards which can be joined mechanically and, on the other hand, floorboards and floor systems provided with such a locking system and a production method to produce such floorboards.
The present invention is particularly suited for use in floating wooden floors and laminate floors, such as massive wooden floors, parquet floors, floors with a surface of veneer, laminate floors with a surface layer of high pressure laminate or direct laminate and the like.
The following description of prior-art technique, problems of known systems as well as objects and features of the invention will therefore as non-limiting examples be aimed mainly at this field of application. However, it should be emphasized that the invention can be used in any floorboards, which are intended to be joined in different patterns by means of a mechanical locking system. The invention may thus also be applicable to floors which are glued or nailed to the sub floor or floors with a core and with a surface of plastic, linoleum, cork, varnished fiberboard surface and the like.
In the following text, the visible surface of the installed floorboard is called "front side", while the opposite side of the floorboard facing the subfloor is called "rear side". By “floor surface” is meant the major outer flat part of the floorboard, which is opposite to the rear side and which is located in one single plane. Bevels, grooves and similar decorative features are parts of the front side but they are not parts of the floor surface. By "laminate floor" is meant a floor having a surface, which consists of melamine impregnated paper, which has been compressed under pressure and heat. "Horizontal plane" relates to a plane, which is extended parallel to the outer part of the floor surface. "Vertical plane" relates to a plane perpendicular to the horizontal plane.
The outer parts of the floorboard at the edge of the floorboard between the front side and the rear side are called "joint edge". By "joint edge portion" is meant a part of the joint edge of the floorboard. By "joint" or "locking system" are meant cooperating connecting means, which interconnect the floorboards vertically and/or horizontally. By "mechanical locking system" is meant that joining can take place without glue. Mechanical locking systems can in many cases also be joined by glue. By "vertical locking" is meant locking parallel to the vertical plane. As a rule, vertical locking consists of a tongue, which cooperates with a tongue groove. By "horizontal locking" is meant locking parallel to the horizontal plane. By "joint opening" is meant a groove which is defined by two joint edges of two joined floorboards and which is open to the front side. By "joint gap" is meant the minimum distance between two joint edge portions of two joined floorboards within an area, which is defined by the front side and the upper part of the tongue next to the front side. By “open joint gap” is meant a joint gap, which is open towards the front side. By "visible joint gap" is meant a joint gap, which is visible to the naked eye from the front side for a person walking on the floor, or a joint gap, which is larger than the general requirements on joint gaps established by the industry for various floor types. With “continuous floating floor surface” is meant a floor surface, which is installed in one piece without expansion joints.
Traditional laminate and parquet floors are usually installed floating on an existing subfloor. The joint edges of the floorboards are joined to form a floor surface, and the entire floor surface can move relative to the subfloor. As the floorboards shrink or swell in connection with the relative humidity RH varying during the year, the entire floor surface will change in shape.
Floating floors of this kind are usually joined by means of glued tongue and groove joints. In laying, the boards are brought together horizontally, a projecting tongue along the joint edge of one board being inserted into a tongue groove along the joint edge of an adjoining board. The tongue and groove joint positions and locks the floorboards vertically and the glue locks the boards horizontally. The same method is used on both long side and short side, and the boards are usually laid in parallel rows long side against long side and short side against short side.
In addition to such traditional floating floors, which are joined by means of glued tongue and groove joints, floorboards have been developed in recent years, which do not require the use of glue but which are instead joined mechanically by means of so-called mechanical locking systems. These systems comprise locking means, which lock the boards mechanically horizontally and vertically without glue. The vertical locking means are generally formed as a tongue, which cooperates with a tongue grove. The horizontal locking means comprising a locking element, which cooperates with a locking groove. The locking element could be formed on a strip extending from the lower part of the tongue groove or it could be formed on the tongue. The mechanical locking systems can be formed by machining the core of the board. Alternatively, parts of the locking system such as the tongue and/or the strip can be made of a separate material, which is integrated with the floorboard, i.e., already joined with the floorboard in connection with the manufacture thereof at the factory.
The floorboards can be joined mechanically by various combinations of angling, snapping-in, vertical change of position such as the so-called vertical folding and insertion along the joint edge. All of these installation methods, except vertical folding, require that one side of the floorboard, the long or short side, could be displaced in locked position. A lot of locking systems on the market are produced with a small play between the locking element and the locking grove in order to facilitate displacement. The intention is to produce floorboards, which are possible to displace, and which at the same time are connected to each other with a fit, which is as tight as possible. A very small displacement play of for instance 0.01-0.05 mm is often sufficient to reduce the friction between wood fibers considerably. According to The European Standard EN 13329 for laminate floorings joint openings between floorboards should be on an average ≤ 0.15 mm and the maximum level in a floor should be ≤ 0.20 mm. The aim of all producers of floating floors is to reduce the joint openings as much as possible. Some floors are even produced with a pre-tension where the strip with the locking element in locked position is bended backwards towards the sub floor and where the locking element and the locking groove press the panels tightly against each other. Such a floor is difficult to install.
Wooden and laminate floors are also joined by gluing or nailing to the subfloor. Such gluing/nailing counteracts movements due to moisture and keeps the floorboards joined. The movement of the floorboards occurs about a center in each floorboard. Swelling and shrinking can occur by merely the respective floorboards, and thus not the entire floor surface, changing in shape.
Floorboards that are joined by gluing/nailing to the subfloor do not require any locking systems at all. However, they can have traditional tongue and groove joints, which facilitate vertical positioning. They can also have mechanical locking systems, which lock and position the floorboards vertically and/or horizontally in connection with laying.
The advantage of floating flooring is that a change in shape due to different degrees of relative humidity RH can occur concealed under baseboards and the floorboards can, although they swell and shrink, be joined without visible joint gaps. Installation can, especially by using mechanical locking systems, take place quickly and easily and the floor can be taken up and be laid once more in a different place. The drawback is that the continuous floor surface must as a rule be limited even in the cases where the floor consists of relatively dimensionally stable floorboards, such as laminate floor with a fiberboard core or wooden floors composed of several layers with different fiber directions. The reason is that such dimensionally stable floors as a rule have a change in dimension, which is about 0.1% corresponding to about 1 mm per meter when the RH varies between 25% in winter and 85% in summer. Such a floor will, for example, over a distance of ten meters shrink and swell about 10 mm. A large floor surface must be divided into smaller surfaces with expansion strips, for example, every tenth or fifteenth meter. Without such a division, it is a risk that the floor when shrinking will change in shape so that it will no longer be covered by baseboards. Also the load on the locking system will be great since great loads must be transferred when a large continuous surface is moving. The load will be particularly great in passages between different rooms.
According to the code of practice established by the European Producers of Laminate Flooring (EPLF), expansion joint profiles should be installed on surfaces greater than 12 m in the direction of the length of the individual flooring planks and on surfaces greater than 8 m in the width direction. Such profiles should also be installed in doorways between rooms. Similar installation guidelines are used by producers of floating floors with a surface of wood. Expansion joint profiles are generally aluminum or plastic section fixed on the floor surface between two separate floor units. They collect dirt, give an unwanted appearance and are rather expensive. Due to these limitations on maximum floor surfaces, laminate floorings have only reached a small market share in commercial applications such as hotels, airports, and large shopping areas.
Unstable floors, such as homogenous wooden floors, may exhibit still greater changes in shape. The factors that above all affect the change in shape of homogenous wooden floors are fiber direction and kind of wood. A homogenous oak floor is very stable along the fiber direction, i.e., in the longitudinal direction of the floorboard. In the transverse direction, the movement can be 3% corresponding to 30 mm per meter or more as the RH varies during the year. Other kinds of wood exhibit still greater changes in shape. Floorboards exhibiting great changes in shape can as a rule not be installed floating. Even if such an installation would be possible, the continuous floor surface must be restricted significantly.
The advantage of gluing/nailing to the subfloor is that large continuous floor surfaces can be provided without expansion joint profiles and the floor can take up great loads. A further advantage is that the floorboards do not require any vertical and horizontal locking systems, and they can be installed in advanced patterns with, for example, long sides joined to short sides. This method of installation involving attachment to the subfloor has, however, a number of considerable drawbacks. The main drawback is that as the floorboards shrink, a visible joint gap arises between the boards. The joint gap can be relatively large, especially when the floorboards are made of moisture sensitive wood materials. Homogenous wooden floors that are nailed to a subfloor can have joint gaps of 3 - 5 mm. The distance between the boards can be irregularly distributed with several small and some large gaps, and these gaps are not always parallel. Thus, the joint gap can vary over the length of the floorboard. The large joint gaps contain a great deal of dirt, which penetrates down to the tongue and prevents the floorboards from taking their original position in swelling. The installation methods are time-consuming, and in many cases the subfloor must be adjusted to allow gluing/ nailing to the subfloor.
It would therefore be a great advantage if it were possible to provide a floating floor without the above drawbacks, in particular a floating floor which
a) May comprise a large continuous surface without expansion joint profiles,
b) May comprise moisture sensitive floorboards, which exhibit great dimensional changes as the RH varies during the year.
The present invention relates to locking systems, floorboards and floors which make it possible to install floating floors in large continuous surfaces and with floorboards that exhibit great dimensional changes as the relative humidity (RH) changes. The invention also relates to production methods and production equipment to produce such floors.
A first object of the present invention is to provide a floating floor of rectangular floorboards with mechanical locking systems, in which floor the size, pattern of laying and locking system of the floorboards cooperate and allow movements between the floorboards. According to an embodiment of the invention, the individual floorboards can change in shape after installation, i.e., shrink and swell due to changes in the relative humidity. This can occur in such a manner that the change in shape of the entire floor surface can be reduced or preferably be eliminated while at the same time the floorboards remain locked to each other without large visible joint gaps.
A second object is to provide locking systems, which allow a considerable movement between floorboards without large and deep dirt-collecting joint gaps and/or where open joint gaps could be excluded. Such locking systems are particularly suited for moisture sensitive materials, such as wood, but also when large floating floors are installed using wide and/or long floorboards.
The terms long side and short side are used in the description to facilitate understanding. The boards can according to the invention also be square or alternately square and rectangular, and optionally also exhibit different patterns and angles between opposite sides.
It should be particularly emphasized that the combinations of floorboards, locking systems and laying patterns that appear in this description are only examples of suitable embodiments. A large number of alternatives are conceivable. All the embodiments that are suitable for the first object of the invention can be combined with the embodiments that describe the second object of the invention. All locking systems can be used separately in long sides and/or short sides and also in various combinations on long sides and short sides. The locking systems having horizontal and vertical locking means can be joined by angling and/or snapping-in. The geometries of the locking systems and the active horizontal and vertical locking means can be formed by machining the edges of the floorboard or by separate materials being formed or alternatively machined before or after joining to the joint edge portion of the floorboard.
According to a first embodiment, a floating floor comprises rectangular floorboards, which are joined by a mechanical locking system. The joined floorboards have a horizontal plane, which is parallel to the floor surface, and a vertical plane, which is perpendicular to the horizontal plane. The locking system has mechanically cooperating locks for vertical joining parallel to the vertical plane and for horizontal joining parallel to the horizontal plane of a first and a second joint edge. The vertical locks comprise a tongue, which cooperates with a groove, and the horizontal locks comprise a locking element with a locking surface cooperating with a locking groove. The format, installation pattern and locking system of the floorboards are designed in such a manner that a floor surface of 1 * 1 meter can change in shape in at least one direction at least 1 mm when the floorboards are pressed together or pulled apart. This change in shape can occur without visible joint gaps.
According to a second embodiment, a locking system is provided for mechanical joining of floorboards, in which locking system the joined floorboards have a horizontal plane which is parallel to the floor surface and a vertical plane which is perpendicular to the horizontal plane. The locking system has mechanically cooperating locks for vertical joining parallel to the vertical plane and for horizontal joining parallel to the horizontal plane of a first and a second joint edge. The vertical locks comprise a tongue, which cooperates with a groove and the horizontal of a locking element with a locking surface, which cooperates with a locking groove. The first and the second joint edge have upper and lower joint edge portions located between the tongue and the floor surface. The upper joint edge portions are closer to the floor surface than the lower. When the floorboards are joined and pressed against each other, the two upper joint edge portions are spaced from each other and one of the upper joint edge portions in the first joint edge overlaps a lower joint edge portion in the second joint edge.
According to several preferred embodiments of this invention, it is an advantage if the floor comprises rather small floorboards and many joints, which could compensate swelling and shrinking. The production tolerances should be rather small since well-defined plays and joint openings are generally required to produce a high quality floor according to the invention.
Small floorboards are however difficult to produce with the required tolerance since they have a tendency to turn in an uncontrolled manner during machining. The main reason why small floorboards are more difficult to produce than large floorboards is that large floorboard has a much large area, which is in contact with a chain and a belt during the machining of the edges of the floorboards. This large contact area keeps the floorboards fixed by the belt to the chain in such a way that they cannot move or turn in relation to the feeding direction, which may be the case when the contact area is small.
Production of floorboards is essentially carried out in such manner that a set of tools and a floorboard blank are displaced relative to each other. A set of tools comprises preferably one or more milling tools which are arranged and dimensioned to machine a locking system in a manner known to those skilled in the art.
The most used equipment is an end tenor, double or single, where a chain and a belt are used to move the floorboard with great accuracy along a well defined feeding direction. Pressure shoes and support unites are used in many applications together with the chain and the belt mainly to prevent vertical deviations. Horizontal deviation of the floorboard is only prevented by the chain and the belt.
The problem is that in many applications this is not sufficient, especially when panels are small.
A third object of the present invention is to provide equipment and production methods which make it possible to produce floorboards and mechanical locking systems with an end tenor but with better precision than what is possible to accomplish with known technology.
Equipment for production of building panels, especially floorboards, comprises a chain, a belt, a pressure shoe and a tool set. The chain and the belt are arranged to displace the floorboard relative the tool set and the pressure shoe, in a feeding direction. The pressure shoe is arranged to press towards the rear side of the floorboard. The tool set is arranged to form an edge portion of the floorboard when the floorboard is displaced relative the tool set. One of the tools of the tool set forms a guiding surface in the floorboard. The pressure shoe has a guiding device, which cooperates with the guiding surface and prevents deviations in a direction perpendicular to the feeding direction and parallel to the rear side of the floorboard.
It is known that a grove could be formed on the rear side of a floorboard and that a ruler could be inserted into the groove to guide the floorboards when they are displaced by a belt that moves the boards on a table. It is not known that special guiding surfaces and guiding devices could be used in an end tenor where a pressure shoe cooperates with a chain.
A fourth object of the present invention is to provide a large semi-floating floor of rectangular floorboards with mechanical locking systems, in which floor the format, installation pattern and locking system of the floorboards are designed in such a manner that a large semi-floating continuous surface, with length or width exceeding 12 m, could be installed without expansion joints.
Figs 3a-3e show locking systems.
The strength of a mechanical locking system is of great importance in large continuous floating floor surfaces. Such large continuous surfaces are defined as a floor surface with length and/or width exceeding 12 m. Very large continuous surfaces are defined as floor surfaces with length and/or width exceeding 20 m. There is a risk that unacceptable joint gaps will occur or that the floorboards will slide apart, if the mechanical locking system is not sufficiently strong in a large floating floor. Dimensionally stable floorboards, such as laminate floors, which show average joint gaps exceeding 0.2 mm, when a tensile load of 200 kg/m is applied, are generally not suitable to use in a large high quality floating floor. The invention could be used to install continuous floating floors with a length and/or width exceeding 20 m or even 40 m. In principle there are no limitations. Continuous floating floors with a surface of 10,000 m2 or more could be installed according to invention.
Such new types of floating floors where the major part of the floating movement, in at least one direction, takes place between the floorboards and in the mechanical locking system are hereafter referred to as Semi-floating Floors.
Practical experiments demonstrate that a floor with a surface of veneer or laminate and with a core of a fiberboard-based panel, for instance a dimensionally stable high quality HDF, can be manufactured so as to be highly dimensionally stable and have a maximum dimensional change in home settings of about 0.5 – 1.0 mm per meter. Such semi-floating floors can be installed in spaces of unlimited size, and the maximum play can be limited to about 0.1 mm also in the cases where the floorboards have a width of preferably about 120 mm. It goes without saying that still smaller floorboards, for instance 0.4 * 0.06 m, are still more favorable and can manage large surfaces also when they are made of materials that are less stable in shape. According to a first embodiment, a new type of semi-floating floor where the individual floorboards are capable of moving and where the outer dimensions of the floor need not be changed. This can be achieved by optimal utilization of the size of the boards, the mobility of the locking system using a small play and a small joint gap, and the installation pattern of the floorboards. A suitable combination of play, joint gap, size of the floorboard, installation pattern and direction of laying of the floorboards can thus be used in order to wholly or partly eliminate movements in a floating floor. Much larger continuous floating floors can be installed than is possible today, and the maximum movement of the floor can be reduced to the about 10 mm that apply to current technology, or be completely eliminated. All this can occur with a joint gap which in practice is not visible and which is not different, regarding moisture and dirt penetration, from traditional 0.2 m wide floating floorboards which are joined in parallel rows by pretension or with a very small displacement play which does not give sufficient mobility. As a non-limiting example, it can be mentioned that the play 20 and the joint gap 21 in dimensionally stable floors should preferably be about 0.1 - 0.2 mm.
An especially preferred embodiment according to the invention is a semi-floating floor with the following characteristics: The surface layer is laminate or wood veneer, the core of the floorboard is a wood based board such as MDF or HDF, the change in floor length Δ TL is at least 1,0 mm when a force F of 100 kg/m is used, the change in floor length Δ TL is at least 1.5 mm when a force F of 200 kg/m is used, average joint gaps do not exceed 0.15 mm when the force F is 100 kg/m and they do not exceed 0.20 mm when the force F is 200 kg/m.
The function and joint quality of such semi-floating floorboards will be similar to traditional floating floorboards when humidity conditions are normal and the size of the floor surface is within the generally recommended limits. In extreme climate conditions or when installed in a much larger continuous floor surface, such semi-floating floorboard will be superior to the traditional floorboards. Other combinations of force F, change in floor length Δ TL and joint gap 21 could be used in order to design a semi-floating floor for various application.
Figs 4a and 4b show how a locking system can be designed so as to allow a floating installation of floorboards, which comprise a moisture sensitive material. In this embodiment, the floorboard is made of homogeneous wood.
Figs 5a and 5b illustrate the long side joint of three floorboards 1, 1' and 1" with the width W.
Figs 6b and 6c illustrate an embodiment where there is a small play 22 between the overlapping joint edge portions 16, 18, which facilitate horizontal movement in the locking system.
In the above-preferred embodiments, the overlapping joint portion 18 is made in the tongue side, i.e., in the joint edge having a tongue 10. This overlapping joint portion 18 can also be made in the groove side, i.e., in the joint edge having a groove 9. Figs 6d and 6e illustrate such an embodiment. In
Figs 7a-7b illustrate that it is advantageous if the upper joint edge 18, which overlaps the lower 16, is located on the tongue side 4a. The groove side 4b can then be joined by a vertical motion to a side 4a, which has no tongue, according to
Although only preferred embodiments are specifically illustrated and described herein, it will be appreciated that many modifications and variations of the present invention are possible in light of the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.